Paravane



April 25, 1961 F. FEHLNER 2,981,220

PARAVANE Original Filed July 27, 1954 2 Sheets-Sheet 1 III! FIG. I.

158 I25 I46 [69 m I67 I30 I29 use I23 I65 7 I72 I68 I73 125 INVENTOR LEOEFEHLNER BY azmzdh m'z/ ATTORNEYS April 25, 1961 L. F. FEHLNER 2,981,220

PARAVAN E Original Filed July 27, 1954 2 Sheets-Sheet 2 g dlllil IN VENTOR LEO R FEHLNER ATTORNEYS on the towing cable, and in an erratic and 2,981,220 Patented Apr. 25, 1961 PARAVANE Leo F. Fehlner, Bethesda, Md.

Driginal application July 27, 1954, Ser. No. 446,185,

(Granted under Title 35, US. Code (1952), sec. 266) The invention described herein maybe manufactured and used by or for the Government of the United States of America for Governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to improvements in paravanes and more particularly to paravanes having cambered hydrofoils with high lift-to-drag and lift-to-weight ratios, and which maintain an accurate operational depth This application is' a division of copending parent application Serial No. 446,185, filed July 27, 1954, now Patent No. 2,960,960. Y

Generally, paravanes have been towedby a towing vessel at a substantial angle rearward from the towpoint on the ship by a cableattached to the paravane body since presently'used paravanes have a high inherent drag which causes the paravane to lag appreciably rearward of the towing point. Further, .paravanes are usually equipped with a depth control device sensitive to static pressure changes to position the paravane at a specific operational depth. Some of these depth control devices in combination with the conventional paravane construction have caused the paravane to excessively oscillate or hunt in the water in finding an equilibrium towing position. This hunting action of the paravane produces dynamic loads which result in undesirable repeated stress inefficient manner of towing the device.

The present invention embodies a buoyant or nonbuoyant paravane capable of carrying a cable quickly away from the ship and to be towed therefrom. The paravane utilizes a cambered hydrofoil, hereinafter called a paravane wing. The paravane wing is similar to an aircraft wing and is equipped withhorizontal and lateral stabilizing; surfaces. The cooperation of the aerodynamically. designed -cambered paravane wing with the stabilized surfaces causes the paravane to operate nearly abearn of the tow point on the ship, while the depth of the-paravane is determined; by controlling;the,attitude of the paravan erelative to its direction of travel. I i rThe camberedparavane wing operates in a similar manner as an aircraft wing in a banked attitude, wherein I the. inclination of the wing may be changed byvarying the lift forces over :the paravanes cambered surfaces of the paravane, through the towline, will not be greatly affected by the drag forces of the paravane, and wherein the normal towing position will accordingly be substantially abeam of the vessels towing point. The high resultant lift force inherent in the cambered design of the paravane wing will cause said wing to quickly tow-out, instead of being merely dragged along, and to assume the desired operational position at the end of a substantially taut cable. r

The paravane wing is attached to the towline through a suitable coupling which will enable the paravane wing to pivot continuously about an axis concentric withthe towline and to roll freely'about a horizontal axis and pitch freely about an axis perpendicular to both the roll throughaninduced-changein the relative fiuid flow pattern.th ereon through the. use ofcontrol surfaces, such as; flaps, ailerons, elevators, or the like. In conjunction with-the paravane wing, a depth control'mechanism responsiveto hydrostatic pressure is utilized for motivating the action ofthe control surfaces for differentially varying the fluid flow pattern and, consequently, the lift forces'over the wing. ,Thevariation' of the lift loading on the paravane wing, in response to changes in hydrostatic pressure, -will produce corresponding variations in the attitude ofthe wing. which will result in a corresponding change. in the depth position of the paravane. 4 e ;j',-Fu'rther,- the present invention embodies afparavane' high lift-to-weight ratio.

Ewhenein the pulling force exerted by the to'winglyessel axis and the tow cable, which axes are fixed by operational requirements. Accordingly, the paravane wing will be operative free of any interfering action from the towline and will tend to remain substantially in its chosen equilibrium position, for independent reaction to changes in hydrostatic pressure. The paravane wing is provided with suitable stability surfaces to furnish a dampening and stabilizing effect which will substantially retard any oscillatory movement of said wing about its vertical or horizontal axis. The paravane wing will quickly tend to return to its equilibrium position of operation after any change in its attitude since it is solely responsive to changes in hydrostatic pressure and not to forces transmitted thereto through the attached towline other than tension.

The paravane wing of the immediate invention is provided with longitudinal stability about its towpoint through the provision of the suitable surface contour, or camber, wherein the resultant of all the hydrodynamic forces acting on said wing will pass through its towing point to substantially eliminate any undesirable unbalancing of said wing from its operative attitude and wherein deviations from this attitude result in moments which tend to restore the paravane to its operative attitude. By isolating the paravane wing in the manner heretofore discussed from any deleterious effects of unbalanced loads arising from the interaction of the hydrodynamic forces and the towline loads, the wing will be free to assume its equilibrium position and will be responsive to small changes in hydrostatic pressures. These hydrostaticpres sure changes will be translated through a simple mechanism into movement of suitable control surfaces regulating the depth of the paravane.

Hence, a broad object of the present invention is to provide a paravane constructed with suitable cambered hydrofoil sections having a high lift-to-drag ratio.

A further object is the provision of a pressure sensitive device highly responsive to small changes in hydro? static pressure and having simple translating mechanism for actuating control surfaces which determine the attitude of the paravane in the water through suitable modi-,

fication of the fluid flow over the paravanes surface.

Another object of the present invention is the provision of 'a' paravane which when towed on the end of a cable assumes an equilibrium position of tow substantially abeam of the towing vessel at a specified depth and continues to remain in this position over a specified speed range. I

A further object'of the invention isthe provision of a paravane having an airplane-type wing and movable control surfaces for controlling the depth of the paravane.

Still another object is to provide a paravane having a movement.- t i i je at e rsss s n cnfi n ist ep v qp of 3 a paravane that during towing will have longitudinal stability about its towline attachment point.

Other objects and manyof the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof and wherein: i

Figure 1 is a perspective view of a preferred embodiment of the invention, in an exaggerated scale for purposes of clarity, showing an airplane-type paravane wing in towing position relative to a towing vessel;

Figure 2 is a plan view, partly in section, of a modification of an embodiment of the invention showing an airplane-type paravane wing having a streamlined body with. elevator-type control surfaces attached thereto;

Figure 3 is a sectional view of the modification shown in Figure 2, taken on a line III-III looking in the direction of the arrows; and

Figure 4 is a side view of the modification shown in Figure 2 showing the paravane in its operative attitude.

Referring now to the drawings, there is shown in Figure 1 a preferred embodiment of the invention comprising a cambered hydrofoil or paravane wing 12, as referred to hereinafter, with a stability surface 14 and flaps 16 integral with the wing. The flaps 16 are alter nately actuated, as shown in the parent application, by a depth controlled mechanism housed within the paravane wing 12 and exposed to thestatic pressure of the fluid in which it is immersed in a manner herein disclosed. The depth control mechanism includes an adjustable member that causes one or the other of the flaps 16 to operate when the depth of submergence of the paravane deviates from a predetermined depth corresponding to thejpar ticular adjustment of the adjustable member.

The paravane wing 12 may be formed inany suitable h geometric shape; however, in the preferred embodiment said wing is constructed with a uniform sweepback about its longitudinal axis and with a top and bottom cambered surface, as described in the parent application. The flaps 16 are connected to the depth control mechanism through flap shafts automatically operated by the depth control mechanism.

The longitudinal stability surface 14 is spaced from the hydrofoil 12 and supported in a fixed relation thereto by supporting struts 44, to, thereby remove said surface from the deleterious effect of the slipstream of the fluid flow over the paravane wing so as to provide. a measure of longitudinal stability in excess of. that provided by the wing 12. The struts 44 are shaped so as to form lateral stability surfaces which. provide lateral stability and damping and are hollow in construction and filled with a buoyant material with the exception of conduits for communicating the hydrostatic pressure from pressure vents 16 provided on their surfaces, to the'depth control mechanism. The stability surface 14, also filled with the buoyant material, and its supporting struts 44 are formed with suitable streamlined contours so as to. present an eificient hydrodynamic shape to the fluid. flow about the paravane wing 12, and to thus minimize any possible interference withthe flow over said paravane wing and to minimize the drag. To facilitate maintenance, the paravanes top surface 20 is provided with a number of conventionally constructed accessible covered wells 48 to provide the means for periodical inspections of the flap shafts and of the depth controlmechanism.

In the operation of the preferred embodiment 10, the paravane wing 12 is adjusted to'op'erate at a specific depth within certain design limits by thesuitable adjustment'of the depth control mechanism. The paravane wing is coupled to the tow line 54 by asuitableconnection to the tow point of the paravane. Theparavane wing is placed in a suitable launcher so that the stability surface 14 is facing away from the towing vessel when launched in its operative position in the water.

In launching the preferred embodiment, the paravane wing 12 is jettisoned or dropped from the towing vessel into the water as far away from the side of the vessel as possible to insure that the paravane does not hit the vessels side and to give the paravane an initial attitude on leaving thelauncher whichcauses the paravane to enter the surface of the water and quickly tow out into normal operative position.

In the normal operative towed position, the depth of the paravane is determined by controlling the vertical attitude of the paravane wing 12 relative to its direction of travel. The attitude of the wing is controlled by the variation from a predetermined pressure, set by the adjustable member of the depth control mechanism, of the hydrostatic pressure of the water adjacent the pressure taps 46, which is received by the depth control mechanism, to independently and alternately actuate the flaps 16 ad jacent the trailing edge 38 of said wing 12 and in addition for large changes in operative depth. The hydrostatic pressure is received through the pressure taps 46, located at a suitable distance from the fluid flow over the paravane wing to escape any pressure disturbances created therefrom, and communicated through passageways provided in the buoyant material within struts 44.

'Thus, any change in hydrostatic pressure will cause the paravane to react thereto by a relative change in the banking characteristics of the paravane through a variationin the lift forces over the surface of the paravane wing 12. The variation in lift is produced through a change in the fluid flow pattern over a portion of the paravane wing 12 due tothe actionof the actuated flap 16 on thepath of the fluid flow to reducethe lift and increase the;drag over said portion of the paravane wing.

A modification of the present invention, illustrated in Figures 2-4, comprises a cambered paravane wing 112 provided with a streamlined body 113 secured thereto along the center line of said wing. The wing 112 is provided with lateral stabilizers 114, functioning in amanner similar to the stabilizer 44 of the preferred embodiment, perpendicularly attached'to each wing tip. The depth attitude of the paravane is determined by a pair of horizontal elevators 116 pivotly mounted on the body 113, forward of the wing 112, and controlled by a depth control mechanism 118 provided within a chamber 158 formed within the body 113. The depth control mechanism 118 is powered by a fluid driven propeller 120 rotatably mounted on the front end of thebody 113. As the paravane is, towed, the reaction of the water willcause the propeller to turn, and if the paravane is noted the predetermined depth the propeller through its shaft (as will be more fully explained) will cause theelevators to bring the paravane to the correct depth. The paravane is connected to the towing vessel by a towing cable 54 attached to a tow post 128pivotally secured to the body 113 at the fore and aft position of the center. of gravity of the paravane, and in a manner similar tothatdescribed for the tow cable andtow post in the parent application.

The propeller 120 is secured on a shaft 121,extending within the depth control chamber 158 andprovided with "a beveled gear 122 slidably splined thereon. Thebeveled gear 122 meshes with diametrically opposed beveled gears 123 (only one of which is shown in Fig. 3), to drive them in opposite directions. The beveled gears 123 are formed with facing plane surfaces near the centers. thereof to frictionally engage opposite sides of a friction disc 125 having an axially extending hollow hub 125'. An end of the friction disc 125 is journaled through its hub 125' in a support 1'65 of the pressure responsive bellows 166 andits other end is threadedly engaged witha fixed shaft 127 secured to the body. 113 through a fixed post 126. The end cooperates with a limit stop member 173 to limit the longitudinal motion, of the friction disc 125 relative to'the fiXe'dshaft'127. The opposite end "surfaces provided near the respectivecenter.

characteristics of the paravane.

hunting action. 1 j V In accordance with the present invention, a paravane ;is provided that is towed by a cable from a towing vessel,

which in operation quickly assumes an equilibrium posi- V Ation at a specified depth and continues to remain in this 167 of the slidable bellows 166 isconnected to the gears 122, 123,'and to a yoke'169 through a suitable unitary frame member 129. slidably mounted within a frictionless guide ring 130 fixed to the body 113.

- A compression spring 168 is concentrically mounted with respect tothe bellows 166 to bias the ends 165 and 167 away from'each other. The yoke 169 is coupled to the elevators 116 through'a link 170 pivotally fixed to the yoke 169' and to a member 171 which is fixed to a rotatable shaft 172 on which are suitably mounted the elevators 116. The hydrostatic pressure port 146 is provided on the body 113, in a region where super-velocities of fluid are not expected, toserve as a hydrostatic pressure inlet to the chamber 158 for operative:communication with the bellows 166. Thedepth control chamber 158 is, provided with a removable closure member 148 conforming to the streamlined contours of the body 113. v

" In the operation of the modification 100 of the invention, the cable 54 is attached to thetow post 128 and launchedin a manner similar to the launching, of the preferred embodiment 10, wherein the paravane wing is in a vertical position and the stabilizers 114 are in a horizontal attitude. The fluid driven propeller 120 rotates the shaft 121 to drive the beveled gear 122 and the beveled gears 123 in opposite directions. The gears 123 operatively engage thev friction disc 125 through the plane At a predetermined depth, the friction disc 125 contacts the gears 123 at .their centers and consequently no frictional force is applied to disc 125. The friction disc 125 is rotatably secured to the pressure responsive bellows166, and in threaded engagement with the fixed shaft 127. The end 167 of the slidable bellows 166 is connected to the gears 123 and 122 throughv the unitary frame 129 to form a unitary slidable assembly.

'The yoke 169 is secured to the bellowsend 167 for longitudinal movement with the bellows166 and spring 168, and thus with the unitary frame member 129. Any change in hydrostatic pressure communicated to the depth control mechanism 118 will be transmitted through the unitary frame member 128 to the link 169 andxthrough linkage 170 and 171'to the elevator shaft 172. An increase in depth by the paravane will reduce the length of the bellows 166, and movement of the end 167 will longitudinally displace the gears,.123 ,attached to frame member 129, relative to thefriction disc 125 and thereby cause said disc 125 to threade'dly rotate relative tothefixedfshaft 127 to properly adjust the position of the elevatorushaft 1,72. ,Thus, ch anges instatic pressure, causingdeflections of the bellows 1 6,willbe taken up by the screw connection between the friction disc 125 and the fixed ,shaft 127; to thereby improve the depth keeping The longitudinal motion of the bellows is transmitted to the elevators 116 through the longitudinal movement of the yoke 169 fixed to the frame 129 and coupledto the shaft 172 through the intermediate crank 171 and pivot link 170, to thereby rotate the, elevators 116 for control hunting, @nd'through the high lift-to-drag design of the paravane wing which is ,formediwith cambered surfaces to provide longitudinal stability about the paravanes tow point. p v v J The preferred embodiment and the modifications of the present invention are similar in thataerodynamic prin- C1P S are employed to obtain a high lift paravane wing with an inherent low drag and witha high lift-to-weight ratio for providing a very efficient paravane, which will maintain a towline substantially abeam of the vessels tow point. ,The embodimentsof the present invention utilize cambered paravane wing surfaces designed according to thenon-dimensional coo'rdinants presented herein, and utilize a depth control mechanism responsive to 1 changes in hydrostatic pressure for actuating a mechanism operatively coupled to control surfaces associated with the paravane wing. Suitable actuation of the control surfaces Gil of paravane depth. The rotation of the elevators-produces a relative change in the angle of attack of the elevators,

to thereby produce a relative change in the lift forces over said elevators 116, to thereby control the rise or fall of the paravane relative to its longitudinal axis. As the paravane approaches the correct depth, the bellows 166 elongate to move the gears 122 and 123, and in turn, the elevators 116 in the opposite direction, until the paravane is balanced at the desired depth without. undesirable position over a specified speed range: Accordingly, a

said adjustable fluid flow control means.

much more stable device for maintaining acable' substantiallyabeam of the towing ship is provided through-the action jof the depth control mechanism which prevents produces a modification of the fluid flow pattern about the paravane which results in a variation of the paravanes lift and drag components which determine its attitude in the water and, consequently, its depth.

' Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood, that within 7 the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is: Y 1 1.- A paravane to be towed through water, comprising a streamlined body, a cambered paravane wing secured to an end of said streamlined body, the longitudinal axis of said streamlined body coinciding indirection with a center line of said paravane wing, stability means fixed to said wing and extending perpendicularly therefrom, adjustable fluid fiow control means at said streamlined body for controlling the. position of said paravane in the water, a depth control device secured within said streamlined body, and having a pressure sensitive device responsive to hydrostatic pressure changes at a point of saidparavane, said depth control device including operable means for adjusting said'control means, said operable means being operable in accordance with hydrostatic pressure respouses of said pressure sensitive device. 2. A paravane as defined in claim 1 wherein said stability means comprising surfaces at the ends of said paravanewing:substantially perependicular thereto. ,3. A paravane as defined in claim 1 wherein saidcontrol means comprising surfaces extending from said streamlined bodysubstantially perpendicularly tosaid paravane'wing. Y 4. Aparavane, asdefined in claim 1 wherein said pres sure sensitive device comprises" an inlet exposed toam bient .fluid about said paravane but so as to be substantially free of pressure disturbances created solely by said paravane wing.

fluid 'flow control meansfor controlling'the position of said paravane inthe water, said fluid flow control means controlling the flow of fluid relative to said paravane,

means responsive to the speed of said paravane through the water, a depth control means responsive'to the depth I of said paravane in the water, and means interconnecting said speed responsive means and depth control means to 6. A paravane as defined in claim 5 streamlined body opposite the'first said end.

5. A paravane to be towed through water substantially abeam from a towing vessel, comprising a cambered paravane, a tow post for receiving a tow cable, said tow post being substantially in line with the center of gravity 1]? herein said speed 7 responsive means comprises apropeller atanend of said paravane, a tow post for receiving a tow cable, said tow post being substantially in linewith the center ofzgravity of said paravane, stability means and adjustable fluid flow control means for controlling the position of said paravane in'thewater, said fluid flow controlmeanscontrolling the fiow of fluid relative to said paravane, means re sponsive to the speed of said paravane through the water, adepth control means responsive to the depth of said paravane in the water, andrneans interconnecting said speed responsive means and depth controlmeans to said adjustable fluid flow control means to control the adjustment of said fluid flow control means. V

8. A paravane adapted to be towed by a cable substantially abeam of atowing vessel, comprisingaparavane wing having cambered lower and upper surfaces, a

for controlling the attitude of the paravane, depth control rncansl secured twithin said body, propellervmeans' rota:

tively mountedon the nose of said body and coupled to said depth control device, gear means connected to said I propeller and driven thereby, second gear means meshing with said first gear means and having. plane surfaces near their center portions, a frictiondisc engaging said second gear, means at their'cent ers, said friction dic being coupled to said depth control device, athreaded shaft fixed rela tive to said'body and threadedly engaging thereon said static'pressure on the hydrofoil and operativelycoupled tothe control surfaces for moving such surfaceslrelative tothe hydrofoil to thereby modify the fluid fiow pattern about the cambered surfaces of the hydrofoilfor'producing a variation in lift and drag components and correspending changes in attitude and depth of the paravane.

10. A paravane for carrying a cable substantially abeam from a'towing vesse'L'said' paravane comprising a hydrofoil having major surfaces thereof cambered' ac cording to given non-dimensional coordinates in a man- I nor as to produce inherently low drag'and relatively'high lift-to-weight ratio when towed in a normal substantially 1 vertical operative position to thereby maintain: the cable I substantially abeam of the: towing vessel, astreamlined body extending forwardly ofthe center of the hydrofoil, movable control surfaces extending from said body for modifying fluid flow patterns aboutsaid cambered sur-r faces, speed, responsive means operable in accordance with I the speed of said paravane, and depth control mechanism responsive to changes in hydrostatic pressure on the hy-' drofoil, said speed responsive means and said depth control mechanism being operativelycoupled to the control 7 surfaces for moving such surfaces relative to the hydro '30 I friction disc, said depth control means having a bellows with one end connected to said frictiondisc and a second end coupled to said first and second beveled gear means,

the second end of said'bellows having yoke means secured thereto for longitudinalmovement therewith, and mechanical means coupling said yoke and said elevators for actuationof said elevators in response to the action, of

said bellows. r V y 9. 'A paravane for carrying a cable substantially abe'a'm from a towing vessel, said 'paravane' comprising a'hydrofoil having major surfaces thereof cambered according to given non-dimensional coordinates in a manner asto produce inherently low drag and relatively high lift-toweight ratio when towed in a normal substantially vertical operative position to thereby maintain the cable substantially abeam of the towing vessel, a streamlined body extending forwardly of the center of the hydrofoil, movable control surfaces extending from said body for modifying fiuid flow patterns about said cambered surfaces, and depth control mechanism responsive toichanges in hydrofoil tothereby modify the fluid flow pattern about the cambered surfaces of the hydrfofoil toproduce a. variation in lift and drag components and-corresponding'changes in attitude and idepthof the paravane.

11,. A parava'ne for carrying a cable substantially abeam from a towing yessel, said tparav'ane comprising a hydrofoil having major surfaces thereof cambered according to given non dirnensional coordinates in a manner as to produceinherently low drag and relatively high I lift-to -weight ratio when towed in a normal substantially verticaloperative position to thereby maintain the cable substantially abeam of the towing'vessel, a streamlined body extending'forwar'dly of the center of the hydrofoil, a speedqesponsive' propeller extending from an end of said body, flow control means for; controllably modifying I the fluidflow pattern about the cambered surfaces of said. hydrofoil, and depth control mechanism responsive to changes in speed of said propeller and operatively coupled to said flow control means for controlling said flow control means.

References Cited in the file of this patent UNITED STATES PATENTS Burney Nov. 9, 1920 2,572,442 Burnelli Oct. 23, 1921 2,681,773 

